1. Field of the Invention
This invention relates to a slide valve plate (hereinafter sometimes referred to simply as "plate"), and in particular, a slide valve plate suited to re-use (recycle) and a method of making the same.
2. Description of the Related Art
Conventionally, a new plate for controlling the discharging amount of a molten metal from a molten metal vessel is in general mainly composed of a stationary plate and a movable plate which are secured by metal fixtures to a lower part of the molten metal vessel, and the movable plate is secured with a nozzle at its lower part.
The movable plate is slidingly contacted to the stationary plate, so that orifices formed therein are made agree to discharge the molten metal, or are made disagree to control or stop the issue of the metal.
The plate suffers serious damages by the molten steel while using, and recently from economical pointview, it has eagerly been demanded for its re-using, and there have already been proposed several methods therefor.
FIG. 4 shows a plate capable of re-using. For example, the orifices are especially seriously damaged in the movable plate S or the stationary plate K of the used plate and are hollowed out in circle by a boring process so as to form a through hole 42 into which a cylindrical straight ring 43 is engaged and inserted. Then, the sliding face of the plate is ground to fall into tolerance of the same smoothness as that of a new plate. As a cushioning plate to be furnished to a non-sliding face of the plate, the same cushioning plate as a firstly used cushioning plate is re-used. In FIG. 4, numerals 41, 42 and 44 represent a plate main body, a through hole, an orifice, respectively.
However, according to this method, there was a risk that the straight ring 43 fitted in the through hole 42 would slip out while working.
For improving such matter, when re-producing the through hole of the movable plate S, the overall orifices of the molten metal in the plate are hollowed out, and a cylinder having a ring shaped jaw part is inserted therein and fixed with a mortar (JP-A-5-200531).
As the method disclosed in JP-A-5-200531 inserts the cylinder having the ring shaped jaw part in the hollowed parts and fixes with the mortar, the cylinder can advantageously be prevented from slipping out as happening conventionally, but when removing the cylinder having the damaged ring shaped jaw part and inserting a cylinder having a new ring shaped jaw part so as to fix with the mortar, problems involved are that it is difficult to remove the cylinder of the damaged jaw part, and at the same time the plate itself might be injured.
Especially, when the connection between the jaw part and the plate is cancelled, the plate is injured so that a grinding amount of the plate is increased by the injured amount, and such a problem occurs that difficulty is increased in grinding the sliding face of the plate to fall into tolerance of the same smoothness as that of a new one.
Further, by increasing of the grinding amount, the thickness of the plate is decreased and accordingly the strength thereof is lowered.
The invention has been realized in view of such problems.